Virus–like particles and endophytic bacteria in Paraphysomonas and Chromophysomonas (Chrysophyceae)

An ultrastructural investigation has shown the presence of icosahedral virus–like particles (VLPs) in three species of Paraphysomonas and one species of Chromophysomonas. The VLPs appear to be responsible for the sudden collapse of enrichment cultures of these species. The possible relationship with particles in other algae which are known to be true viruses is discussed. Endophytic bacteria were also observed in two species of Paraphysomonas , where they occurred within distensions of the nuclear envelope. This is the first report of endophytic bacteria in this location in the algae.